Heating chamber with pressure responsive door mounting

ABSTRACT

In a device (1) for the treatment of materials under the action of heat, and if appropriate also pressure, in a heating chamber consisting of a housing (2), containing the heating chamber, having a charging opening for the heating chamber which can be selectively opened or closed by means of a door (4), and a heating device (6), in particular a microwave heating device, for the heating chamber (7), the door (4) is so mounted that when a particular pressure in the heating chamber is exceeded it lifts off from the door frame (2) and is movable into a relief-opening position, out of which position it is moveable back into the original-closed position--after reduction of pressure--either automatically or by the application of force.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a device for the treatment of materials; andmore particularly, it concerns a novel device having a heating chamberwhich is selectively opened and closed by a door.

DESCRIPTION OF THE RELATED ART

Devices of this kind are employed for initiating, promoting and/orcarrying through chemical or physical processes in materials and/or forthe preparation of materials in each case with relatively great heatingand/or simply for the heating of materials for various purposes.

Thereby, there may be involved measures for separation of materialsand/or preparation of materials in particular for the purpose ofanalysis and/or for the preparation of materials, e.g. heating or bakingof foodstuffs for consumption.

With the above-described measures, because of the effect of the heat andevaporation of the material to be heated or of components of thematerial there is a pressure increase in the heating chamber which inparticular in the case of a large volume heating chamber and a largearea closure element can lead to an overloading and thus damaging of theparts retaining the closure element in its closure position. With apressure increase in the heating chamber of only about 0.5 bar, there isin the case of a charging aperture of about 40 cm×40 cm a pressureloading of 800 kg on the inner surface of the closure element.Conventional mounting constructions for the closure element are notdesigned for such a loading. Such a design would also make moredifficult the integration of the mounting elements and further lead to adisadvantageous and costly construction.

The above-described problems are present both when the material istreated in special closable sample containers or is treated directly inthe heating chamber. In the first case, because of the pressureincrease, there often occurs a bursting or exploding of the samplecontainer or containers, whereby the pressure propagates into theheating chamber and places this likewise under pressure. In such devicesor treatments in which the material to be treated is placed directlyinto the heating chamber, the latter is directly set under pressure.

The above-described problems occur with devices of the present kind inthe case both of commercial use and also domestic use. An example of adomestically useable device is e.g. a domestic microwave oven whichlikewise suffers the above-described disadvantages and is also at riskfor the above-mentioned reasons.

SUMMARY OF THE INVENTION

The object of the invention is to protect a device of the kind indicatedin the introduction from an overloading resulting from a damaginginternal pressure.

All solutions in accordance with the invention contribute to theprotection of the device from overloading and thus contribute to aprotection from explosions.

According to one aspect of this invention, there is provided a devicefor the treatment of materials under the action of heat, and ifappropriate, also pressure, in a heating chamber. The device is formedwith a charging aperture which opens into the heating chamber; and thisaperture can be selectively opened and closed by means of a door whichnormally presses against a frame around the aperture. A heating device,such as a microwave generator, is provided for the heating chamber. Thedoor is so mounted that upon a particular pressure in the heatingchamber being exceeded, the door lifts off from the frame and moves to arelief-opened position; and, after the reduction of pressure, the doorcan be moved back into the original position either automatically or bythe application of force.

With the above described configuration in accordance with the invention,an overpressure in the heating chamber is automatically released, sothat overloading cannot arise. The door, standing in its reliefposition, can thereby fulfil a monitoring or indicating function fromwhich it is apparent to the operating person that an overpressure waspresent.

Thereby, a maximum loading of the device or of the door can be limitedby means of the force of a spring which biases the door into its closedposition. In the case of an internal pressure exceeding the therebypredetermined pressure parameter, the door is moved against the biasingforce of the spring, whereby an opening gap appears through which thepressure can escape, whereby the overloading is prevented. With such aconfiguration working can take place with an overpressure in the heatingchamber which is lesser than the bias force.

According to a specific embodiment of the invention, the housing has aset of perforations, whereby an overpressure is prevented from arising,since the overpressure can escape through the perforations. Thisconfiguration in accordance with the invention is suitable for measuresfor the heat treatment of materials which take place at normal pressureor room pressure and/or at an under-pressure in the heating chamber.

According to a further specific embodiment of the invention, a pressuresensor is associated with the heating chamber which together with acontrol or regulation device reduces or so controls the heating powerthat a particular internal temperature is not exceeded or the heating isturned off. In all these cases, the internal temperature is limited orreduced so that through these means a damaging or dangerous increase inthe internal pressure is avoided. This configuration in accordance withthe invention is suitable in particular for combination with theconfiguration in accordance with the invention in particular when theheating device is a microwave heating device. With such a combination,the movable closure element may be the pressure sensitive part of thepressure sensor which brings about a switching off of the microwavepower. By these means, not only is the temperature in the chamberreduced but it is also prevented that microwaves escape to the outsidethrough the gap formed upon movement of the closure element between thelatter and the housing.

Additional specific features of the invention as embodied herein involvefeatures which improve the functions of the device or the mounting ofthe closure element and provide for simple, compact and economicallymanufacturable constructions which also make possible a purposivetreatment and special treatments of the material.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the invention and further advantages which can be achievedthereby will be described in more detail with reference to preferredexemplary embodiments as shown in the accompanying drawings in which:

FIG. 1 is a perspective view showing a device in accordance with theinvention and, in particular, showing a door in a first position;

FIG. 2 is a view similar to FIG. 1 but showing the door in a secondposition; is a view similar to FIG. 1 but showing the door in a secondposition.

FIG. 3 is a fragmentary section view showing one form of door mountingarrangement for the embodiment of FIG. 1;

FIG. 4 is a fragmentary section view showing a door locking arrangementfor the device of FIG. 1; and

FIG. 5 is a front elevational view, partially cut away, of a housing forthe device of FIG. 1, with the door removed;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIGS. 1 and 5, a device 1 according to the presentinvention, comprises; a block-like housing 2 having a front chargingaperture 3 (FIG. 5) which can be selectively opened or closed by meansof a swing door 4, elastically yielding mounts 5 for the swing door 4, aheating device 6, in particular a microwave heating device, for heatinga heating chamber 7 arranged in the housing 2, and an electrical controland/or regulation device 8 which is connected with the associatedcontrol or regulation elements of the device 1 by means of control orsignal lines and is equipped with automatically functioning control andregulation elements and, if appropriate, with a keyboard for manualsetting.

The housing 2 is of block-like form and has a floor wall 9, two sidewalls 11a, 11b, a ceiling wall 12 and a rear wall 13, whereby the frontwall is formed by means of the swing door 4 and closes the frontcharging aperture 3 in its closed position.

As shown in FIG. 1, there is provided a heating device 6. The heatingdevice 6 has a magnetron, which may be arranged e.g. over an opening onthe ceiling wall 12 (not shown) and through which the microwaves arecoupled into the heating chamber 7. The housing 2 is of metal, wherebythe swing door 4 may also be partly of transparent material, e.g. glass.In this case it is however prevented, by measures known per se (metalgrids), that microwaves can emerge through the glass.

In the present configuration, the swing door 4 is mounted swingably bymeans of two yielding joint mounts 5, arranged at the upper and lowercorner regions, respectively, at one side; and the door 4 is closable bymeans of a locking device 14 arranged on the other side. The lockingdevice 14 has an externally accessible handle 14a and a verticallymovable key bolt 14b (shown in FIG. 4) connected therewith inconventional manner. The overall two yielding joint mounts 5 isessentially the same, except that they are arranged in a mirror-imagemanner with regard to a horizontal middle plane. For purposes ofsimplicity, therefore, only the upper yielding joint mount 5 will bedescribed.

The joint 16 of the yielding joint mount 5 consists of a joint partassociated with the housing 2 in the form of a joint bar 17 preferablycircular in cross-section which extends at right angles to the plane ofthe door 4 and which is guided and mounted in a guide hole 18 of amounting piece 19 displaceably along its middle axis, i.e. likewise atright angles to the plane of the door. The joint bar 17 penetrates themounting piece 19 and projects beyond it to the rear, whereby acompression spring 22 is spanned between a thickened bar head 21 and themounting piece 19, which (biases) the joint bar 17 to the rear against astop 23 which may advantageously be formed by means of a stop pieceattached on the housing 2 behind the bar head, here on the ceiling wall12 of the housing.

The joint bar 17 extends forwardly beyond the plane of the chargingaperture 3 (FIG. 5) and engages into a horizontal joint recess 24 (FIG.3) of the swing door 4, with play for movement. Within the swing door 4,the joint bar 17 has a vertical joint bore 25 in which a joint pin 26 ismounted with play for movement, which joint pin is held on the swingdoor 4. The joint recess 24 is so large horizontally that the swing door4 can be swung more than 90°, whereby the door is mounted with thehorizontal limiting walls of the joint recess 24 on the two joint bars17 present. The stop or stops 23 are so positioned that with abutment ofthe bar head or heads 21 due to the biasing of the spring 22, the swingdoor 4 abuts with its abutment surface 20a on the abutment surfaces 20bsurrounding the charging aperture 3, if appropriate by means of a seal(not shown) and thereby closes the heating chamber 7. The later abutmentsurface 20b may also be arranged on a flange 2a surrounding the chargingaperture 3.

Preferably the yielding joint mount 5 is integrated in an adjustmentdevice designated generally with 28 which makes possible an adjustmentand setting of the swing door 4 at right angles to its plane, in orderto adapt the door to the abutment surface 20b taking into considerationthe tolerances present. With the present configuration, the adjustmentdevice 28 is formed by means of a telescopable joint rod 17 whereby itsrear end region has a thread onto which there is screwed a threaded nut29--preferably lockably on the thread--which slightly projects beyondthe rear end of the joint rod 17 and is thus suitable for lengthsetting. A yielding mount 5a is provided in the region of the lockingdevice 14 is formed in substance the same as the yielding mount 5 in theregion of the joint 16--see the same parts with the same referencenumbers--whereby however instead of a joint 16 at the forward end of thelocking bar 17a there is provided a locking recess 31, if appropriatewith an approach slant 31a of the thus formed locking part. The lockingbar 17a is adjustable in the same manner as the joint bar 17. There isto be associated with the locking bar 17a, so far as it is circular, ameans preventing rotation thereof, since it is not secured againstrotation as is the joint bar 17 by means of the joint pin 26 in thedoor.

With the above-described configuration, the yielding joint mounts arearranged on the ceiling wall 12 or under the floor wall 9 and attachedthereto, and the yielding locking device 14 is mounted on the outside onthe associated side wall 11b. Within the scope of the invention,however, other arrangements are possible, e.g. the two joint mounts 5may be mounted on the inside or the outside on the associated side wall11a or integrated therein.

Within the scope of the invention it is possible to correspondinglyretain and mount a lid (not shown) or a swing door arranged on the upperside (not shown).

For a heat treatment process of a material this is placed, preferably inat least one receptacle A (FIG. 5), in the heating chamber 7 and theheating device switched on, whereby the material is heated by means ofthe microwaves directly or also indirectly, as is known per se. Vapoursthereby appearing, and temperature and/or pressure rises connectedtherewith, can increase to such a level in the heating chamber 7 thatthe compression springs 22--dimensioned in accordance with a particularpressure value and exercising a corresponding bias--are overcome and theswing door 4 lifted off from the abutment surface 20b. Hereby, therearises a gap S illustrated in FIG. 2, through which an overpressureexceeding a predetermined pressure value can escape to the outside. Bythese means, the loading of the spring door 4 and its mounting andlocking means is limited to a value so that these parts, with regard totheir strength, need only be made so robust that they can accept thedemands at the predetermined pressure value. This applies naturally alsofor the housing 2, because a higher internal pressure cannot arise.

It is also advantageous to associate with the heating chamber 7 apressure sensor which monitors the internal pressure and at an internalpressure which may be equal to the predetermined pressure value or mayalso correspond to a lesser pressure value, switches off the heatingdevice 6 and in particular a microwave heating device, so that nomicrowaves can escape to the outside through the gap S.

The gap S preferably in the range of 1 to 5 mm.

An above-mentioned pressure sensor may in advantageous manner monitorthe position of the swing door or components mounted on the same; and,in the event of a movement, the pressure sensor may deliver a signal tothe control device 8 (FIG. 1). With the present configuration, twopressure sensors are formed by means of switches or microswitches 33which are preferably arranged between the stop pieces 23--in particulartherein or thereon built-in or built-on--and the rearward ends of thejoint rods 17 and deliver a signal upon lifting off of the swing door 4.

The parts of the yielding joint mount 5 and locking mount 5a may be ofmetal.

As shown in FIG. 5, with the above-described exemplary embodiments,instead of or in addition to the elastically yielding door mount, theremay be provided in a wall or in one or in both side walls 11a, 11b, aset of perforations 35 in a part region 36 of the associated wall. Thepart region 36 is located preferably in the lower region of the housing.The set of perforations comprises a plurality of holes 37 thecross-sectional size of which is so large--taking into consideration thewall thickness and the wavelength of the microwaves--that no microwavesemerge from the holes 37. In the present configuration, circular holesare provided, the cross-sectional size or diameter of which is 2 to 4mm. The thickness of the side wall 11a and also 11b may thereby be about1 mm.

The number of the holes 37 is such that, in the case of a spontaneouspressure increase to be expected, the pressure can escape through theholes 37 without the device 1 suffering damage or exceeding a particularpressure value. With this configuration, a treatment of the material inthe heating chamber 7 is in substance possible only at normal or roompressure.

The perforations 35 are, however, also suitable advantageously incombination with an elastically yieldingly held swing door 4 when theperforations are only so large that despite the perforations there canarise in the heating chamber 7 a pressure exceeding the predeterminedpressure value which brings about the abovedescribed lifting off of thedoor.

The perforations 35 may also be a part of a ventilation system 38 forheating chamber 7. In this case, there is provided at another locationof the housing 2, preferably an opposite location, e.g. in the otherside wall 11b, a second set of perforations 35a in a correspondingmanner, whereby one of the sets of perforations--here the perforations35a--is provided at a suction or pressure device for air or a gas, e.g.an inert gas. In accordance with FIG. 5, the perforations 35a areconnected by means of a collector 39 and a connected pipe or tube line41 with a pump 42 which transports the air or a gas from a gas sourcethrough the heating chamber 7 by suction or pressurisation. Here, acooling and/or flushing device for the heating chamber 7 may beinvolved. In particular in the case of a flushing device fortransporting away vapours out of the heating chamber 7 it isadvantageous to connect the discharge line to a chimney or to a devicefor analyzing the vapours.

With the configuration according to FIG. 5, one or more receptacles Amay be provided which are each sealingly closable by means of areceptacle lid A1 and with each of which an over-pressure valve V isassociated which opens at a receptacle pressure exceeding apredetermined value. Preferably, the associated valve body is thereceptacle lid A1 itself which is biased into its closed position bymeans of a spring element V1, e.g. by means of a settable pressure part,preferably in the form of a setting screw V2.

With the configuration according to FIG. 5, there is provided a carousel45 having a carrier disk 45a and a cover disk 45b, rotatable orswingable to and fro by means of a drive (not shown), whereby thesetting screws V2 are vertically screwed into and preferably accessiblefrom above the cover disk 45b. The receptacles A, with the springelement V1 preferably arranged thereon, are mounted between the settingscrews V2 and the current disk 45a.

I claim:
 1. Device for the treatment of materials under the action ofheat and pressure, in a heating chamber, said device comprising ahousing containing a heating chamber, said housing being formed with acharging aperture for the heating chamber, said aperture beingsurrounded by a door frame on said housing, a pivotal door which can bemoved to selectively open and close said aperture, and a microwaveheating device for the heating chamber, characterized in that:the devicealso includes a first mounting structure which mounts said frame to saidhousing and a second mounting structure which mounts said door to saidframe, one of said mounting structures including a releasable lockingdevice and allowing pivotal movement when the locking device isreleased, and the other mounting structure including a pressureresponsive holding device which permits limited linear movement inresponse to excessive pressure within the chamber.
 2. Device accordingto claim 1, characterized in that, in the relief-opened position thereis a gap between the door frame and the door.
 3. Device according toclaim 1 or 2, characterized in that, the door is elastically biased intoits closed position and is movable transversely of the opening surfaceof the charging aperture.
 4. Device claim 1, characterized in that, thedoor is a swing-lid.
 5. Device claim 1, characterized in that, the dooris arranged at a side of the housing (2).
 6. Device according to claim1, characterized in that, the housing in vertical cross-section has aright-angled or quadratic form and the door likewise has a right-angledor quadratic form.
 7. Device according to claim 1, characterized inthat, the door is pivotably mounted at one side by means of at least onepivot joint and has at the other side, a locking device.
 8. Deviceaccording to claim 7, characterized in that, a elastically yieldingmount is integrated into at least one of the pivot joint and the lockingdevice of the door.
 9. Device according to claim 7, characterized inthat, one of said joint and locking parts is mounted to be displaceabletransversely of the opening surface of the charging aperture and isbiased inwardly.
 10. Device according to claim 9, characterized in that,at least one of the joint and a locking part associated with the housingis formed by means of a bar extending at right angles to the door, whichbar is mounted to be longitudinally displaceable along its middle axisin a guide hole of a mounting piece, and in that the door is pivotallymounted on the door end of the bar.
 11. Device according to claim 10,characterized in that, the joint bar is biased inwardly against a stopby means of a spring.
 12. Device according to claim 11, characterized inthat, a switch is associated with the stop, which, switch delivers tothe associated control device a signal for switching off the heatingdevice.
 13. Device according to claim 1,characterized in that, the dooris mounted to be displaceable from said aperture in at least one ofseveral directions which include movement in parallel to itself andswingable and tiltable movement.
 14. Device according claim 1,characterized in that, there is provided an adjustment device foradjustment of the movable joint part transversely of the opening surfaceof the charging aperture.
 15. Device according to claim 14,characterized in that, the joint bar is telescopable, by means of athreaded nut screwed onto its rearward end or a screwed-in screw. 16.Device according to claim 1 wherein the housing has, in a wall thereof,a set of perforations which are so dimensioned in relation to thethickness of said wall that no microwaves emerge through saidperforations.
 17. Device according to claim 16, characterized in that,there are provided respective sets of perforations in at least two wallsof the housing, and there is provided for one set of perforations aventilation device for a gas for the heating chamber.
 18. Device for thetreatment of materials in accordance with claim 1, characterized inthat,a pressure sensor is associated with the heating chamber, and acontrol or regulation device is associated with the pressure sensor,which control or regulation device so controls the heating power of themicrowave heating device when a particular pressure value in the heatingchamber is exceeded that the pressure in said heating chamber does notexceed a predetermined pressure value.
 19. Device according to claim 18,characterized in that, the pressure sensor detects the movement of thedoor for the purpose of generating a control signal for the control orregulation of the heating power.